Add guarded assistant concept fallback flow

Harden unified KB control flow, telemetry, and 20-case antenna eval runner

Fix auth/retrieval regressions and harden startup diagnostics

Add unified knowledgebase tab and backend domain router

Sync canonical Router KB corpus, Router RAG module, eval harness, and app updates

Add auth diagnostics panel and Playwright auth smoke tests

feat: ship auth0 integration, router data updates, and ui refresh

Initial commit for HF deployment